We propose to develop a mass spectrometry (MS) analysis system and a protocol that can be applied for chemical analysis at the point of care (POC) for medical diagnosis. The aims are to develop (1) a miniature mass spectrometer that has compact size, low cost of ownership and maintenance but with adequate performance for quantitative analysis, and (2) sample cartridges for direct analysis of blood samples and (3) an operational protocol that allows this system to be used by nurses and physicians, who do not need to have special training in chemical analysis using MS. This research team at Purdue University has been consistently pushing the development of technologies and applications to allow MS analysis to be used for POC tests at clinical sites and ultimately for personal health care. Our long term goal is to develop a POC MS system and collaborate with researchers such as those at The University of Texas MD Anderson Cancer Center (UTMDACC) to validate the technology and to incorporate it into drug development to optimize disease therapy. The critical issues in the development of a POC MS system have been identified as the miniaturization of the entire analysis system and the simplification of the analysis protocol. In this R01 project, we propose to develop a complete POC MS analysis system and associated operational protocol based on miniature ion trap and paper spray technologies, and to validate the system for therapeutic drug monitoring with oncology drugs. The expected outcome from the proposed work is the generation of the first POC MS system with a relatively complete solution for therapeutic drug monitoring and with potential for a significant impact on future development of MS-based chemical analysis systems for clinical diagnosis.